**5.3. Edward Tyson**

Tyson15 was born into an affluent merchant family. He performed numerous dissections as a college student, obtained his medical degree at Oxford University and was a lecturer of Anatomy at the Barber-Surgeons Hall in London. Tyson was the first of the comparative anatomists in the modern sense. He did extensive dissections and was the first to use a microscope as part of his anatomical studies. His description of the highly convoluted cetacean brain as well as his recognition of the many homologies with "viviparous quadrupeds", rather than the fishes that they externally resembled, constituted a major landmark contribution to the history of biology (Kruger 2003).

In *Phocaena, or, The anatomy of a porpess dissected at Gresham Colledge, with a preliminary discourse concerning anatomy and natural history of animals* (1680), he noted that "What we have here is a signal Example of the same between Land-Quadrupeds and Fishes; for if we view a *Porpess* on the outside, there is nothing more than a fish; for if we view a *Porpess* on the inside, there is nothing less. (...) It is viviparous, does give suck, and hath all its Organs so contrieved according to the standard of them in Land-Quadrupeds; that one would almost think of it to be such, but it lives in the Sea, and hath but two fore-fins." Adding later "The structure of the viscera and inward parts have so great an Analogy [*sic*] and resemblance to those of Quadrupeds, that we find them here almost the same. The greatest

<sup>15</sup> *b*. 20 January 1651 Clevedon, near Bristol, Somerset, England; *d*. 1 August 1708, London, England.

difference from them seems to be in the external shape, and wanting feet. But here too we observed that when the skin and flesh was taken off, the forefins did very well represent an Arm, there being the *Scapula*, an of *Humeri*, the *Ulna*, and *Radius*, and bone of the *Carpus*, the *Metacarp*, and 5 *digiti* curiously joynted. The Tayle too does very well supply the defect of feet both in swimming as also leaping in the water, as if both hinder feet were colligated into one, though it consisted not of articulated bones but rather Tendons and Cartilages."

Tyson's description of the internal anatomy of the porpoise is remarkable, particularly when it comes to its nervous system (Kruger 2003). In many ways he thought that the "porpess" was the transitional link between terrestrial mammals and fish.

In his monograph Tyson surveyed contributions from previous authors. He corresponded with John Ray (see below). Ray had also dissected a porpoise (an exercise on which he reported in a published form in 1671), nine years before Tyson but was far more superficial and added very little to what other authors such as Rondelet had done. Tyson met Ray around 1683 and the latter invited Tyson to contribute to Willughby's *De Historia Piscium* (Montagu 1943, p. 103).

Tyson was critical of encyclopedic approaches and relying on classical authors when it came to natural history. He set new standards in terms of direct observation and comparative anatomy. He also established an understanding of homology not seen since Aristotle. He proved to be a very competent observer of internal anatomy and he saw comparative anatomy as a means to explain the Great Chain of Being (or *scala naturae* or ladder of nature) as proposed by Plato and Aristotle.
